Clinical predictors of longer survival in patients with BRAF<sup>V600</sup>-mutated metastatic melanoma receiving immunotherapy prior to BRAF/MEK inhibition in the metastatic setting.
Authors: Adriana Matutino Kahn, Curtis Perry, Katrina Etts, Harriet M. Kluger, Mario Sznol
Journal: Journal of Clinical Oncology (2022)

9555 Background: Patients with advanced BRAF V600 -mutated melanoma are typically treated with immunotherapy in the first-line setting, followed by BRAF/MEKi upon disease progression based on an absolute 20% improvement in 2-year overall survival over initial treatment with BRAF/MEKi in the DREAMseq trial. Our goal was to identify clinical predictors of longer survival for patients treated in our institution with this approach. Methods: We identified 40 patients with BRAF V600 -mutated metastatic melanoma treated at our institution from 2011 to 2020 with immunotherapy followed by BRAF/MEKi upon progression. Clinical data were collected and analyzed by Cox regression and Kaplan-Meier methods. Favorable outcome was defined as survival &gt; 2 years (y) after starting BRAF/MEKis. Results: Median follow up was 33 months (m, 3 – 172 m). Median age was 54 y (20 - 83). Most patients were female (n = 24, %). Most patients were initially treated with ipilimumab plus nivolumab (n = 34, 85%), with 13 of these patients (38%) tolerating all 4 cycles of initial ipilimumab. Adverse events of any grade were seen in 28 (70%) patients after first-line immunotherapy, with the most common being hepatitis, colitis, hypothyroidism, rash, and fatigue. Median duration of first-line immunotherapy was 3.5 m (.75 - 42.5 m). Most common sites of progression on immunotherapy were lymph nodes (n = 14, 35%), liver (n = 12, 30%), bone (n = 10, 25%) and brain (n = 10, 25%). Prior to BRAF/MEKis, median ECOG-PS was 1 (0-4) and median LDH was 268 mg/dL (151 - 11,300). Most common BRAF/MEKi regimen was dabrafenib plus trametinib (n = 34, 85%). Adverse events of any grade were seen in 30 (75%) patients, with the most common being fever, fatigue, nausea, and vomiting. Best response to BRAF/MEKi was CR (n = 4, 10%), PR (n = 26, 65%), SD (n = 4, 10%) and PD (n = 6, 15%), and at the data cutoff, 35 (87.5%) patients progressed on BRAF/MEKi. Median duration of BRAF/MEK inhibition was 7 m (0.5 – 106 m). Median survival since starting BRAF/MEKi was 19.2 m (1.7 – 106 m). On multivariable analyses assessing predictors of survival, presence of bone metastases after disease progression on first-line immunotherapy was associated with worse 2-year survival after initiation of BRAF/MEKi (OR 2.5, 95% CI, 0.51-5.6, p = 0.0121). Other factors, such as ECOG-PS 0-2, normal LDH prior to BRAF/MEKi, and age at metastatic diagnosis &lt; 60 years were not significantly associated with longer survival after initiation of BRAF/MEKi. Conclusions: We showed that the presence of bone metastases upon progression on first-line immunotherapy was associated with worse 2-y survival on salvage BRAF/MEKi for patients with BRAF V600 -mutated metastatic melanoma. Predictive and prognostic biomarkers for long-term response to both immunotherapy and BRAF/MEKi are needed to optimize treatment strategies and patient outcomes.